fs/proc/kcore.c

   1 /*
   2  *      fs/proc/kcore.c kernel ELF core dumper
   3  *
   4  *      Modelled on fs/exec.c:aout_core_dump()
   5  *      Jeremy Fitzhardinge <jeremy@sw.oz.au>
   6  *      ELF version written by David Howells <David.Howells@nexor.co.uk>
   7  *      Modified and incorporated into 2.3.x by Tigran Aivazian <tigran@veritas.com>
   8  *      Support to dump vmalloc'd areas (ELF only), Tigran Aivazian <tigran@veritas.com>
   9  *      Safe accesses to vmalloc/direct-mapped discontiguous areas, Kanoj Sarcar <kanoj@sgi.com>
  10  */
  11
  12 #include <linux/mm.h>
  13 #include <linux/proc_fs.h>
  14 #include <linux/user.h>
  15 #include <linux/capability.h>
  16 #include <linux/elf.h>
  17 #include <linux/elfcore.h>
  18 #include <linux/vmalloc.h>
  19 #include <linux/highmem.h>
  20 #include <linux/init.h>
  21 #include <asm/uaccess.h>
  22 #include <asm/io.h>
  23
  24 #define CORE_STR "CORE"
  25
  26 #ifndef ELF_CORE_EFLAGS
  27 #define ELF_CORE_EFLAGS 0
  28 #endif
  29
  30 static struct proc_dir_entry *proc_root_kcore;
  31
  32 static int open_kcore(struct inode * inode, struct file * filp)
  33 {
  34         return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
  35 }
  36
  37 static ssize_t read_kcore(struct file *, char __user *, size_t, loff_t *);
  38
  39 static const struct file_operations proc_kcore_operations = {
  40         .read           = read_kcore,
  41         .open           = open_kcore,
  42 };
  43
  44 #ifndef kc_vaddr_to_offset
  45 #define kc_vaddr_to_offset(v) ((v) - PAGE_OFFSET)
  46 #endif
  47 #ifndef kc_offset_to_vaddr
  48 #define kc_offset_to_vaddr(o) ((o) + PAGE_OFFSET)
  49 #endif
  50
  51 /* An ELF note in memory */
  52 struct memelfnote
  53 {
  54         const char *name;
  55         int type;
  56         unsigned int datasz;
  57         void *data;
  58 };
  59
  60 static struct kcore_list *kclist;
  61 static DEFINE_RWLOCK(kclist_lock);
  62
  63 void
  64 kclist_add(struct kcore_list *new, void *addr, size_t size)
  65 {
  66         new->addr = (unsigned long)addr;
  67         new->size = size;
  68
  69         write_lock(&kclist_lock);
  70         new->next = kclist;
  71         kclist = new;
  72         write_unlock(&kclist_lock);
  73 }
  74
  75 static size_t get_kcore_size(int *nphdr, size_t *elf_buflen)
  76 {
  77         size_t try, size;
  78         struct kcore_list *m;
  79
  80         *nphdr = 1; /* PT_NOTE */
  81         size = 0;
  82
  83         for (m=kclist; m; m=m->next) {
  84                 try = kc_vaddr_to_offset((size_t)m->addr + m->size);
  85                 if (try > size)
  86                         size = try;
  87                 *nphdr = *nphdr + 1;
  88         }
  89         *elf_buflen =   sizeof(struct elfhdr) +
  90                         (*nphdr + 2)*sizeof(struct elf_phdr) +
  91                         3 * ((sizeof(struct elf_note)) +
  92                              roundup(sizeof(CORE_STR), 4)) +
  93                         roundup(sizeof(struct elf_prstatus), 4) +
  94                         roundup(sizeof(struct elf_prpsinfo), 4) +
  95                         roundup(sizeof(struct task_struct), 4);
  96         *elf_buflen = PAGE_ALIGN(*elf_buflen);
  97         return size + *elf_buflen;
  98 }
  99
 100
 101 /*****************************************************************************/
 102 /*
 103  * determine size of ELF note
 104  */
 105 static int notesize(struct memelfnote *en)
 106 {
 107         int sz;
 108
 109         sz = sizeof(struct elf_note);
 110         sz += roundup((strlen(en->name) + 1), 4);
 111         sz += roundup(en->datasz, 4);
 112
 113         return sz;
 114 } /* end notesize() */
 115
 116 /*****************************************************************************/
 117 /*
 118  * store a note in the header buffer
 119  */
 120 static char *storenote(struct memelfnote *men, char *bufp)
 121 {
 122         struct elf_note en;
 123
 124 #define DUMP_WRITE(addr,nr) do { memcpy(bufp,addr,nr); bufp += nr; } while(0)
 125
 126         en.n_namesz = strlen(men->name) + 1;
 127         en.n_descsz = men->datasz;
 128         en.n_type = men->type;
 129
 130         DUMP_WRITE(&en, sizeof(en));
 131         DUMP_WRITE(men->name, en.n_namesz);
 132
 133         /* XXX - cast from long long to long to avoid need for libgcc.a */
 134         bufp = (char*) roundup((unsigned long)bufp,4);
 135         DUMP_WRITE(men->data, men->datasz);
 136         bufp = (char*) roundup((unsigned long)bufp,4);
 137
 138 #undef DUMP_WRITE
 139
 140         return bufp;
 141 } /* end storenote() */
 142
 143 /*
 144  * store an ELF coredump header in the supplied buffer
 145  * nphdr is the number of elf_phdr to insert
 146  */
 147 static void elf_kcore_store_hdr(char *bufp, int nphdr, int dataoff)
 148 {
 149         struct elf_prstatus prstatus;   /* NT_PRSTATUS */
 150         struct elf_prpsinfo prpsinfo;   /* NT_PRPSINFO */
 151         struct elf_phdr *nhdr, *phdr;
 152         struct elfhdr *elf;
 153         struct memelfnote notes[3];
 154         off_t offset = 0;
 155         struct kcore_list *m;
 156
 157         /* setup ELF header */
 158         elf = (struct elfhdr *) bufp;
 159         bufp += sizeof(struct elfhdr);
 160         offset += sizeof(struct elfhdr);
 161         memcpy(elf->e_ident, ELFMAG, SELFMAG);
 162         elf->e_ident[EI_CLASS]  = ELF_CLASS;
 163         elf->e_ident[EI_DATA]   = ELF_DATA;
 164         elf->e_ident[EI_VERSION]= EV_CURRENT;
 165         elf->e_ident[EI_OSABI] = ELF_OSABI;
 166         memset(elf->e_ident+EI_PAD, 0, EI_NIDENT-EI_PAD);
 167         elf->e_type     = ET_CORE;
 168         elf->e_machine  = ELF_ARCH;
 169         elf->e_version  = EV_CURRENT;
 170         elf->e_entry    = 0;
 171         elf->e_phoff    = sizeof(struct elfhdr);
 172         elf->e_shoff    = 0;
 173         elf->e_flags    = ELF_CORE_EFLAGS;
 174         elf->e_ehsize   = sizeof(struct elfhdr);
 175         elf->e_phentsize= sizeof(struct elf_phdr);
 176         elf->e_phnum    = nphdr;
 177         elf->e_shentsize= 0;
 178         elf->e_shnum    = 0;
 179         elf->e_shstrndx = 0;
 180
 181         /* setup ELF PT_NOTE program header */
 182         nhdr = (struct elf_phdr *) bufp;
 183         bufp += sizeof(struct elf_phdr);
 184         offset += sizeof(struct elf_phdr);
 185         nhdr->p_type    = PT_NOTE;
 186         nhdr->p_offset  = 0;
 187         nhdr->p_vaddr   = 0;
 188         nhdr->p_paddr   = 0;
 189         nhdr->p_filesz  = 0;
 190         nhdr->p_memsz   = 0;
 191         nhdr->p_flags   = 0;
 192         nhdr->p_align   = 0;
 193
 194         /* setup ELF PT_LOAD program header for every area */
 195         for (m=kclist; m; m=m->next) {
 196                 phdr = (struct elf_phdr *) bufp;
 197                 bufp += sizeof(struct elf_phdr);
 198                 offset += sizeof(struct elf_phdr);
 199
 200                 phdr->p_type    = PT_LOAD;
 201                 phdr->p_flags   = PF_R|PF_W|PF_X;
 202                 phdr->p_offset  = kc_vaddr_to_offset(m->addr) + dataoff;
 203                 phdr->p_vaddr   = (size_t)m->addr;
 204                 phdr->p_paddr   = 0;
 205                 phdr->p_filesz  = phdr->p_memsz = m->size;
 206                 phdr->p_align   = PAGE_SIZE;
 207         }
 208
 209         /*
 210          * Set up the notes in similar form to SVR4 core dumps made
 211          * with info from their /proc.
 212          */
 213         nhdr->p_offset  = offset;
 214
 215         /* set up the process status */
 216         notes[0].name = CORE_STR;
 217         notes[0].type = NT_PRSTATUS;
 218         notes[0].datasz = sizeof(struct elf_prstatus);
 219         notes[0].data = &prstatus;
 220
 221         memset(&prstatus, 0, sizeof(struct elf_prstatus));
 222
 223         nhdr->p_filesz  = notesize(&notes[0]);
 224         bufp = storenote(&notes[0], bufp);
 225
 226         /* set up the process info */
 227         notes[1].name   = CORE_STR;
 228         notes[1].type   = NT_PRPSINFO;
 229         notes[1].datasz = sizeof(struct elf_prpsinfo);
 230         notes[1].data   = &prpsinfo;
 231
 232         memset(&prpsinfo, 0, sizeof(struct elf_prpsinfo));
 233         prpsinfo.pr_state       = 0;
 234         prpsinfo.pr_sname       = 'R';
 235         prpsinfo.pr_zomb        = 0;
 236
 237         strcpy(prpsinfo.pr_fname, "vmlinux");
 238         strncpy(prpsinfo.pr_psargs, saved_command_line, ELF_PRARGSZ);
 239
 240         nhdr->p_filesz  += notesize(&notes[1]);
 241         bufp = storenote(&notes[1], bufp);
 242
 243         /* set up the task structure */
 244         notes[2].name   = CORE_STR;
 245         notes[2].type   = NT_TASKSTRUCT;
 246         notes[2].datasz = sizeof(struct task_struct);
 247         notes[2].data   = current;
 248
 249         nhdr->p_filesz  += notesize(&notes[2]);
 250         bufp = storenote(&notes[2], bufp);
 251
 252 } /* end elf_kcore_store_hdr() */
 253
 254 /*****************************************************************************/
 255 /*
 256  * read from the ELF header and then kernel memory
 257  */
 258 static ssize_t
 259 read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
 260 {
 261         ssize_t acc = 0;
 262         size_t size, tsz;
 263         size_t elf_buflen;
 264         int nphdr;
 265         unsigned long start;
 266
 267         read_lock(&kclist_lock);
 268         proc_root_kcore->size = size = get_kcore_size(&nphdr, &elf_buflen);
 269         if (buflen == 0 || *fpos >= size) {
 270                 read_unlock(&kclist_lock);
 271                 return 0;
 272         }
 273
 274         /* trim buflen to not go beyond EOF */
 275         if (buflen > size - *fpos)
 276                 buflen = size - *fpos;
 277
 278         /* construct an ELF core header if we'll need some of it */
 279         if (*fpos < elf_buflen) {
 280                 char * elf_buf;
 281
 282                 tsz = elf_buflen - *fpos;
 283                 if (buflen < tsz)
 284                         tsz = buflen;
 285                 elf_buf = kzalloc(elf_buflen, GFP_ATOMIC);
 286                 if (!elf_buf) {
 287                         read_unlock(&kclist_lock);
 288                         return -ENOMEM;
 289                 }
 290                 elf_kcore_store_hdr(elf_buf, nphdr, elf_buflen);
 291                 read_unlock(&kclist_lock);
 292                 if (copy_to_user(buffer, elf_buf + *fpos, tsz)) {
 293                         kfree(elf_buf);
 294                         return -EFAULT;
 295                 }
 296                 kfree(elf_buf);
 297                 buflen -= tsz;
 298                 *fpos += tsz;
 299                 buffer += tsz;
 300                 acc += tsz;
 301
 302                 /* leave now if filled buffer already */
 303                 if (buflen == 0)
 304                         return acc;
 305         } else
 306                 read_unlock(&kclist_lock);
 307
 308         /*
 309          * Check to see if our file offset matches with any of
 310          * the addresses in the elf_phdr on our list.
 311          */
 312         start = kc_offset_to_vaddr(*fpos - elf_buflen);
 313         if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
 314                 tsz = buflen;
 315
 316         while (buflen) {
 317                 struct kcore_list *m;
 318
 319                 read_lock(&kclist_lock);
 320                 for (m=kclist; m; m=m->next) {
 321                         if (start >= m->addr && start < (m->addr+m->size))
 322                                 break;
 323                 }
 324                 read_unlock(&kclist_lock);
 325
 326                 if (m == NULL) {
 327                         if (clear_user(buffer, tsz))
 328                                 return -EFAULT;
 329                 } else if (is_vmalloc_addr((void *)start)) {
 330                         char * elf_buf;
 331                         struct vm_struct *m;
 332                         unsigned long curstart = start;
 333                         unsigned long cursize = tsz;
 334
 335                         elf_buf = kzalloc(tsz, GFP_KERNEL);
 336                         if (!elf_buf)
 337                                 return -ENOMEM;
 338
 339                         read_lock(&vmlist_lock);
 340                         for (m=vmlist; m && cursize; m=m->next) {
 341                                 unsigned long vmstart;
 342                                 unsigned long vmsize;
 343                                 unsigned long msize = m->size - PAGE_SIZE;
 344
 345                                 if (((unsigned long)m->addr + msize) <
 346                                                                 curstart)
 347                                         continue;
 348                                 if ((unsigned long)m->addr > (curstart +
 349                                                                 cursize))
 350                                         break;
 351                                 vmstart = (curstart < (unsigned long)m->addr ?
 352                                         (unsigned long)m->addr : curstart);
 353                                 if (((unsigned long)m->addr + msize) >
 354                                                         (curstart + cursize))
 355                                         vmsize = curstart + cursize - vmstart;
 356                                 else
 357                                         vmsize = (unsigned long)m->addr +
 358                                                         msize - vmstart;
 359                                 curstart = vmstart + vmsize;
 360                                 cursize -= vmsize;
 361                                 /* don't dump ioremap'd stuff! (TA) */
 362                                 if (m->flags & VM_IOREMAP)
 363                                         continue;
 364                                 /*
 365                                  * we may access memory holes, then use
 366                                  * ex_table. checking return value just for
 367                                  * avoid warnings.
 368                                  */
 369                                 vmsize = __copy_from_user_inatomic(
 370                                         elf_buf + (vmstart - start),
 371                                         (char *)vmstart, vmsize);
 372                         }
 373                         read_unlock(&vmlist_lock);
 374                         if (copy_to_user(buffer, elf_buf, tsz)) {
 375                                 kfree(elf_buf);
 376                                 return -EFAULT;
 377                         }
 378                         kfree(elf_buf);
 379                 } else {
 380                         if (kern_addr_valid(start)) {
 381                                 unsigned long n;
 382
 383                                 n = copy_to_user(buffer, (char *)start, tsz);
 384                                 /*
 385                                  * We cannot distingush between fault on source
 386                                  * and fault on destination. When this happens
 387                                  * we clear too and hope it will trigger the
 388                                  * EFAULT again.
 389                                  */
 390                                 if (n) {
 391                                         if (clear_user(buffer + tsz - n,
 392                                                                 n))
 393                                                 return -EFAULT;
 394                                 }
 395                         } else {
 396                                 if (clear_user(buffer, tsz))
 397                                         return -EFAULT;
 398                         }
 399                 }
 400                 buflen -= tsz;
 401                 *fpos += tsz;
 402                 buffer += tsz;
 403                 acc += tsz;
 404                 start += tsz;
 405                 tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen);
 406         }
 407
 408         return acc;
 409 }
 410
 411 static int __init proc_kcore_init(void)
 412 {
 413         proc_root_kcore = proc_create("kcore", S_IRUSR, NULL, &proc_kcore_operations);
 414         if (proc_root_kcore)
 415                 proc_root_kcore->size =
 416                                 (size_t)high_memory - PAGE_OFFSET + PAGE_SIZE;
 417         return 0;
 418 }
 419 module_init(proc_kcore_init);